“It’s absolutely the highest and best use for that building,” Hagan said. “It would be fantastic for Downtown.”

The ambitious project could cost $65 million or more, Hagan said.

The lobby of the 38-story building would include the hotel lobby, a restaurant, retail space and a separate entrance for apartment residents.

Parking for the building would remain on floors five through eight. The eighth floor, which serves as the roof of the parking garage, could be turned into a terrace area with a “green roof,” a pool and other amenities.

Around 171 hotel rooms would be built on floors nine to 17. The apartments would take floors 18 to 36. The hotel would operate the building’s round rooftop restaurant space.

“Conceptually, the plan is genius,” Hagan said. “If you’ve ever been to the roof, it has the best views in the city, the best views in the state of Tennessee. It’s really amazing.”

One Hundred North Main LLC, a Nevada-based limited liability company, agreed last year to purchase the building from the Zimmerman Revocable Trust for $5 million. The registered agent for One Hundred North Main is Isaac Thomas, who has ties to Memphis and Israel. Thomas’ grandfather, Al Thomas, developed the Claridge House building.

Myron Zimmerman acquired the 38-story office building, which was built in 1965 and includes 792,873 square feet, from Sidney Kohl in 1978 for $10 million.

The 430-foot-tall building sits on one acre at Main Street and Adams Avenue. The Shelby County Assessor of Property’s 2013 appraisal is $3.8 million.

The former Union Planters Bank building for years was a popular spot for legal offices because of its proximity to the courts and has a number of long-term tenants, but the condition of the building has suffered in recent years.

While the Downtown office market has suffered, the area experienced a surge in housing development from 2000 to 2010, which resulted in increases in housing units and residential population. According to population estimate, the 2013 residential population of Downtown is estimated to be almost 24,000, an 18 percent increase since 2000.

Local tourism and hospitality officials have long said Downtown needed more hotel rooms to be able to attract larger conventions and gatherings to the Memphis Cook Convention Center.